In the art of weaving it is well known to provide a weft or filling yarn storage and feeder device or simply "feeder" which operates to store weft yarn for use by the loom, normally a shuttleless loom. The device includes a yarn collecting drum on which weft yarn from a supply source is wound temporarily and then removed under controlled, uniform tension. Such devices eliminate the wide variations in yarn tension which occur when a yarn is delivered from a supply source such as a cone or package, and permits the yarn to be fed to the loom at a substantially constant tension. This art is exemplified by U.S. Pat. No. 3,776,480 to John B. Lawson granted Dec. 4, 1973 and U.S. Pat. No. 3,853,153 granted Dec. 10, 1974 to A. H. Van Duyhoven et al. Typically, such feeders may have either a rotary drum upon which the yarn is wound as the drum is driven by a suitable motive source such as an electric motor or, the feeders may incorporate a stationary drum with an orbiting flyer driven by, say, an electric motor and engaging the weft yarn to apply it to the surface of the stationary drum. For purposes of the present disclosure, reference will be made to the so-called stationary drum feeder although it should be understood that the present invention has equal application to rotary drum feeders.
It is also known in the art to equip feeders of the type just discussed with tension devices arranged upstream of the feeder to impart some predetermined level of tension into the weft yarn being advanced from a weft yarn storage supply to the feeder. These tension devices may include means for automatically stopping the loom in the event of weft yarn breakage or undue slackening of the yarn in the area of the tension unit. Exemplifications of such arrangements are found in U.S. Pat. No. 1,516,885 granted Nov. 25, 1924 to L. T. Houghton and U.S. Pat. No. 2,202,323 granted May 28, 1940 to W. T. Sullivan. These devices as well as other automatic loom stopping devices are positioned in the weft yarn feed path and operate conventionally to actuate pneumatic, electric eye or mechanical switch control circuits which are adapted to stop the weaving loom.
In conventional weaving operations heddles are raised which, in turn, raise warp yarns to create an opening or shed. The filling or weft yarn is then inserted through the shed from one side of the loom to the other. A single crossing of the weft yarn through the shed is called a "pick". Weft storage feeders of the type contemplated herein will normally store enough weft yarn on the drums to equal several pick lengths. Of course, in the event the weft yarn being conveyed from the supply source to the feeder is interrupted, the weft yarn stored on the feeder drum will ultimately become exhausted if the loom continues to operate. In that event, the yarn or "pick" when inserted into the shed will produce a defect. This results from the fact that in almost every case the final length of broken yarn on the feeder drum is less than the length required for the pick to extend from one side of the loom to the other. In consequence of the insertion of a short pick into the fabric the loom attendant must insure that the loom is stopped and then proceed with the laborious task of removing the short pick. This, of course, results in much down time in the weaving operation. Additionally, and equally significant, when the loom is restarted the area of the fabric where the broken pick has been removed and a new pick of proper length has been inserted will often show a defect due to the fact that the new pick will not precisely position itself in the location where the short pick was removed. Thus, it is evident that it is highly desirable to insure that short picks are not inserted into the fabric during the weaving operation and, moreover, that the loom is not stopped simply as a result of false signals produced as a result of mere slackening of the weft supply yarn in the zone of the feeder tension unit.
In operation with looms which employ a variety of different weft yarns it is normal to utilize a separate feeder for accomodating each of the several different weft or filling yarns. It will be quite obvious that while a pick of one specific weft yarn is being inserted into the fabric the other weft supply yarns are inactive. That is to say, the further weft yarns are withheld from entry to the shed. Commonly, a selected one of the multiplicity of different weft yarns may have a plurality of picks sequentially inserted into the shed before a different weft yarn is selected for filling insertion. During these intervals when the weft yarns are inactive it follows that their companion feeders and the related tension units are inactive. Due to the various vibrations and other conditions surrounding the normal weaving operation it readily occurs that the weft supply yarns which are stationary become slack between their sources of supply and the tension devices. Recognizing that the tension devices utilized with feeders are commonly of the "gate" type of, say, the type sold as Model UTC 2003-1by the Steel Heddle Manufacturing Company, Greenville, South Carolina, the tension devices respond to the slackening tension by assuming a closed position. This motion can operate a switch arranged with the tension unit to deliver a signal to the automatic loom stopping device thereby arresting operation of the loom. This, of course, is a highly undesirable condition since the signal is false in that the weft yarn supply is intact and has simply fallen slack due to the aforementioned vibrations.
On the other hand, if, in fact, the closing of the gate type tension arises from the fact that the weft supply yarn has been interrupted as by a breaking, it becomes most desirable that the loom be halted immediately. Otherwise, the feeder will have collected the yarn up to the point where the break has occurred and will supply that yarn as a filling into the fabric, generally resulting in the previously discussed short pick occurring. Significantly, the present invention operates only when two signals simultaneously occur. That is, a signal from the feeder tension device indicating that the weft yarn from the supply source has been interrupted and a signal indicating that the feeder motor is operating. By this ingenious arrangement the present invention avoids the possibility of false signals occurring due to simple slackening of the weft supply yarn in the zone of the feeder tension unit and, at the same time, avoids insertion of short picks in the fabric by shutting down the loom when the feeder motor is operating and slackened weft supply yarn is sensed in the zone of the feeder tension device. Slack yarn will not occur when the feeder is operating because the feeder, drawing yarn from the weft supply, imparts enough tension on the yarn in the region of the tension device to hold the weft yarn taut so long as the weft yarn being delivered off the supply is not broken. Thus, it is logical that if the gates of the tension device close while the feeder motor is running, the supply weft yarn is broken.
Therefore, it is one object of the present invention to provide means and method for preventing false signals inducing stoppage of the weaving loom.
Another object of the present invention is to provide means and method for avoiding the insertion of short picks into fabric being woven on a loom equipped with a weft yarn storage and feeder device.
Still another object of the present invention is to provide means and method for arresting operation of a weaving loom in response to simultaneous signals derived from a tension device associated with the weft yarn feeding device indicating an interruption in the weft supply to the feeder coupled with a companion signal indicating that the motor of the feeder is operational to provide a demand for weft yarn from the weft supply source which would normally establish the requisite tension in the weft yarn to preclude its being slack in the area of the tension device.
Other objects of the invention will impart the obvious and will in part be described hereinafter.